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Universal Sampling

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lindsey wright

on 1 April 2014

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Transcript of Universal Sampling

Rapid PCR
Ethical Considerations

- Cost benefit calculations (if unfordable it will be unavailable to patients and healthcare providers)
- If this test becomes a norm and is done more often due to higher availability women may feel uncomfortable with it (though women were surveyed on the subject and 85% felt okay with this)

Study Background
1 in 3200
infants will be effected by neonatal HSV. Annually
infants in the US are infected with HSV.
of those children will develop a CNS disease that has a high risk of death and is resistant to treatments.
Hypothesis & Objective
Rapid PCR is just as
as the previously used TaqMan PCR and will take less time to process and receive results regarding positive or negative result for HSV-1 and HSV-2 in the genital tract of women in labor. Making it more effective in a
Any women that is going into labor, 18 years or older and English speaking. Non-pregnant women with repeated herpetic genital lesions.
Non-English speaking, not in labor, not of consenting age.

Pop Quiz!
1. What is the main benefit of switching to Rapid PCR verse TaqMan PCR?
Results are available faster!
2.How many women were tested?
Study Design:
Controlled Experiment; Samples of genital secretions collected from two different groups of women (Pregnant women in labor and non-pregnant women with repeated herpetic genital lesions). As well as, an original buffer solution used as the control group.
Samples are then analyzed by both Rapid PCR and TaqMan PCR to compare sensitivity level.
This process is extremely important when testing pregnant women who could have HSV unknowingly and then pass it on to their children during labor.
TaqMan PCR:
- Extremely high accuracy rate
-Testing can only be done in a lab setting (typically off site and tests must be driven there and back)
- Takes 4 hours to complete test
In a clinical setting they have found that simply checking the mothers vagina for lesions is ineffective in decreasing rates of children becoming infected with HSV from their mothers during birth. Making this device crucial for diagnosis of HSV.
Rapid PCR:
- Should have high accuracy
- Can be tested in the clinical setting
- Takes about two hours to complete
- 207 of 716 where found to have HSV with rapid PCR, while 212 of 716 where found positive with Taqman PCR. Meaning that Rapid PCR is slightly less accurate.
-False positive = interventions are made which are unneeded
-False negative = child is exposed to HSV

3. What does PCR stand for?
Polymerase Chain Reaction
Not So Fun Fact:
University of Washington Departments of Obstetrics & Gynecology, Laboratory Medicine and Epidemiology
To test the accuracy and efficiency of the Rapid PCR (Polymerase Chain Reaction) device against the current gold standard TaqMan PCR when testing for HSV (Herpes Simplex Virus)
To develop a rapid quantitative real-time polymerase chain reaction (PCR) to detect
herpes simplex virus (HSV) in the genital secretions of women that may be used in labor.
University of Washington Medical Center
The Rapid PCR took on average 2 hours to complete in the clinical setting. The rapid test had a positive predictive value of 96.7% and a negative predictive value of 99.6% in a population with HSV shedding.
PCR Comparison
- Only 732 women were tested total
- It was only in one location
- The study has not been repeated
However, one is being conducted that is nearly identical...
-16 people were excluded due to false positives with the controls, leading to possible skewed results
"Rapid HSV PCR provides results with excellent sensitivity and specificity within a time frame that could inform clinical decision making for identifying infants at risk of neonatal HSV infection."
Expert Device vs. Rapid PCR
GeneXpert only collects samples from two different groups:
1) Women with active HSV lesions
2) Laboring women
HSV lesions in laboring women is an exclusion criteria in GeneXpert and it was not in the other study. GeneXpert also has a follow-up phone call with laboring women to see how they and their baby are doing. The GeneXpert device is also quicker - it only takes
1 hour
to get results
Gardella, C. (2010). rapid polymerase chain reaction assay to detect herpes simplex virus in the genital tract of women in labor. NIH Public Access, 15(6), 1209-1216.
Full transcript